The Vega advanced third generation posterior stabilized total knee arthroplasty system enables the restoration of range of motion for high demanding daily activities - A 5-years follow-up study.

BACKGROUND: The Vega System® PS (Aesculap AG, Tuttlingen, Germany) is an advanced, third generation fixed implant that aims to mimic natural knee kinematics by optimizing pivotal motion while reducing surface stress. This study evaluated mid-term survival and clinical outcomes, including range of motion (ROM) of the modern posterior stabilized implant in order to analyse whether this biomechanically successful implant reaches good results in situ. METHODS: The first 100 patients to receive the Vega PS System for total knee arthroplasty were invited to take part in this single centre, single surgeon study. Of these, 84 patients were clinically assessed 5-6 years postoperatively. Data which was obtained during this follow-up examination included revision data, range of motion and clinical scores. RESULTS: The 5-year survival rate for exchange of any component was 97.6%, whereby two patients required replacement of the polyethylene gliding surface. Secondary patella resurfacing was performed in 7 patients. Significantly improved results in comparison to the preoperative state could be obtained at the follow-up: KOOS improved from 39.4 to 78.8, SF-12 PCS improved from 32.1 to 42 SF-12 MCS improved from 46 to 53.8 and patella pain improved from 2.7 to 0.3. The mean ROM of the 84 patients after 5 years was 133.1° and mean total KSS was 189.9. DISCUSSION & CONCLUSIONS: This study demonstrates a high survival rate of the Vega PS System® and significant improvements in clinical outcomes 5 years after implantation. The obtained mean ROM indicates that this implant provides good flexibility of the knee joint, allowing a high number of activities. However, due to the rate of secondary patella implantation, routine resurfacing of the patella for all PS TKA cases is highly recommended. CLINICAL TRIALS REGISTRATION: The study was registered at clinicaltrials.gov (NCT02802085).

Topical Treatment Is Effective and Safe for Acute Ankle Sprains: The Multi-Center Double-Blind Randomized Placebo-Controlled TRAUMED Trial.

BACKGROUND: Topical NSAIDs are widely used to treat ankle sprains. Traumed (Tr14) gel is a multicomponent formulation, demonstrating inflammation-resolution properties. METHODS: This multicenter, double-blind trial investigated the efficacy and safety of Tr14 gel versus placebo gel and non-inferiority versus 1% diclofenac gel, applied 3×/day for 7 days after acute lateral ankle sprain (EudraCT Number: 2016-004792-50). The primary outcome was AUC for pain on passive movement, assessed by VAS from baseline to Days 4 and 7. RESULTS: The trial population included 625 patients aged 18 to 78 years. The AUC scores were 187.88 and 200.75 on Day 4 (p = 0.02) and 294.14 and 353.42 on Day 7 (p < 0.001) for Tr14 and placebo, respectively. For Tr14 compared to diclofenac, the AUC scores were 187.50 and 197.19 on Day 4 (p = 0.3804) and 293.85 and 327.93 on Day 7 (p = 0.0017), respectively. On the FAAM-ADL subscale, Tr14 was superior to placebo and non-inferior to diclofenac at all time points. Time to 50% pain improvement was lowest for Tr14 (6.0 days), compared to placebo (7.1 days) and diclofenac (7.0 days). Adverse events were uncommon and minor. CONCLUSIONS: Tr14 gel is effective and safe in acute ankle sprains, compared to placebo gel and diclofenac gel, and has faster pain resolution. TRIAL REGISTRATION: The trial was registered in clinicaltrialsregister.eu, EudraCT number 2016-004792-50 on 07.06.2017.

Stimulation of human bone marrow mesenchymal stem cells by electromagnetic transduction therapy - EMTT.

Many different pulsed electromagnetic field (PEMF) devises have been clinically used to stimulate healing processes, but many procedures are still without supporting basic research data. The aim of this study was to investigate a new modified pulsed electromagnetic field therapy: electromagnetic transduction therapy (EMTT). EMTT is technically based on high-intensive PEMFs with a magnetic field strength between 80 and 150 mT. The effect of EMTT for a 10-min session three times a week on human bone marrow mesenchymal stem cells (MSCs) was evaluated by assessing cell viability, gene expression of bone regenerative factors and VEGF-A (vascular endothelial growth factor) secretion after 7 and 14 days of treatment. No negative or toxic effects of EMTT on MSCs in vitro were observed in the applied test frame. The VEGF-ELISA at day 7 of EMTT treatment with 80 mT showed a significant higher VEGF concentration compared to untreated control group. In conclusion, high-intensive electromagnetic impulses showed no harmful effects on MSC cultures in our study. The enhancement of the proangiogenic factor VEGF in MSCs on day 7 indicates a substantial role in cell-stimulating effect of EMTT. Further in vitro and in vivo studies should differentiate specific stimulating and regenerating effects of EMTT impulses in soft tissue engineering. Specific electromagnetic characteristics have to be determined to optimize electromagnetic treatment options in orthopedic surgery and traumatology and soft tissue treatment options.

Current Consensus for Rehabilitation Protocols of the Surgically Repaired Acute Mid-Substance Achilles Rupture: A Systematic Review and Recommendations From the "GAIT" Study Group.

Surgical repair of acute mid-substance Achilles tendon ruptures is performed in active patients, but the postoperative rehabilitation program is often based on the experience of the surgeon or therapist, rather than on evidence-based protocols. The aim of the study is to establish an evidence-based protocol for rehabilitation. This study is a consensus statement. The "GAIT" study group (German, American, and Italian Tendon), an informal collection of 4 experienced foot and ankle surgeons, met to address the question of what items they felt were important relative to rehabilitate a surgically repaired Achilles tendon acute rupture. Thirty-three statements were formulated. A value of 100% agreement by all the members was set to produce a proposed consensus statement. A value of 80% consensus was set to produce "strong recommendation." A systematic review of the literature was also performed. The GAIT group reach 100% agreement on the average postoperative non-weightbearing for 2.3 weeks, the foot in plantarflexion for the first 4 weeks, avoiding ROM exercises beyond neutral, and both stretching and eccentric exercise, not started before 12 weeks. Concentric bilateral heel raises should be performed after 6 weeks, and the average return to initiate sports, was 24.4 weeks. The use of a 1/8th-1/4th inch heel cushions in daily shoes after 8 weeks, the use of an antigravity treadmill for rehabilitation, and the return to sports based on heel raise repetitions is strongly recommended. Given lack of established verified protocols, the recommendations by our experienced panel should be considered. These proposed consensus statements could be used as a basis for larger controlled trials, and develop best practices.

Long-term Efficacy of Percutaneous Epidural Neurolysis of Adhesions in Chronic Lumbar Radicular Pain: 10 Year Follow-up of a Randomized Controlled Trial.

BACKGROUND: No long-term follow-up data exist in any treatment for chronic radicular pain occurring with disc pathology and after failed back surgery. A previous randomized controlled trial (RCT) has proven efficacy in short-term follow-up as an evidence-based effective therapeutic option. OBJECTIVES: Long term data is needed to determine the efficacy and cost- effectiveness of minimal invasive procedures. The present study reports 10 year follow-up results from the randomized trial. STUDY DESIGN: A prospective, randomized, placebo-controlled, interventional clinical trial. A power calculation was based on a previous feasibility trial. SETTING: University medical centers. METHODS: After a 4 year enrollment phase, 381 patients with chronic radicular pain persisting beyond 4 months, who failed conservative treatments, were screened. Ninety patients were enrolled. Patients were randomly assigned to receive percutaneous epidural lysis of adhesions or placebo with concealed allocation in permuted blocks of 4 to 8 patients each, and stratified by treatment center. The primary outcomes were a mean change of the Oswestry Disability Index (ODI) scores and Visual Analog Scale (VAS), one and 10 years after intervention. For each rating scale an analysis of variance with the within-patient factor time (baseline, one year follow-up, 10 year follow-up) and the between-patient factor treatment (lysis, placebo) was used. RESULTS: Homogeneity was shown at baseline between the groups. The ODI and VAS scores were significantly better one and 10 years in the lysis group vs the control group. The ODI in the lysis group improved from 55.3 ± 11.6 to 9.6 ± 9.3 after one year and to 11.7 ± 14.2 after 10 years. The placebo group also improved from 55.4 ± 11.5 to 30.7 ± 14.2 after one year and to 24.8 ± 12.0 after 10 years. The VAS improved from 6.7 ± 1.1 to 1.2 ± 1.1 after one year and to 1.5 ± 1.4 after 10 years in the lysis group and from 6.7 ± 1.1 to 2.8 ± 1.5 after one year and to 2.9 ± 1.3 after 10 years after placebo intervention. The statistical difference of the ODI and VAS between the treatment and control groups remain significant up to 10 years. No treatment-related severe adverse effects occurred within the 10 years, but minor transient neurological effects were seen directly after the intervention. LIMITATIONS: The long-term effects of single treatment components cannot be specified as no imaging examination was performed at 10 year follow-up. A large variety of unanalyzed noninvasive treatments were done within the 10 years. Some patients did not clearly remember the intervention after 10 years. Uncontrolled effects such as higher inhomogeneity of biometric properties, concomitant therapies, pain tolerance level, or just social effects could occur, but were not analyzed in the trial. CONCLUSION: This is the first 10 year follow-up report of a placebo-controlled RCT showing efficacy of the minimally invasive percutaneous adhesiolysis procedure for patients with chronic lumbosacral radicular pain. No alternative evidence-based treatment modality with 10 year follow-up is available to be recommended. This procedure should be considered as the first treatment option for patients with chronic lumbosacral radicular pain.

An Ex Vivo Bone Defect Model to Evaluate Bone Substitutes and Associated Bone Regeneration Processes.

The increased incidence of bone defects, especially in cases of comminuted fractures or bone tumor resections demands suitable bone grafts and substitutes. The aim of this study was to establish an ex vivo bone defect model to evaluate new bone substitutes and associated repair processes under controlled conditions. Femoral heads derived from patients undergoing total hip replacement were cut into cylinders (20 mm diameter, 7 mm height). A central bone defect (6 mm diameter, 5 mm depth) was inserted centrally. The bone slides were cultured for 28 days and viability was evaluated by lactate dehydrogenase and alkaline phosphatase assay, and Calcein-AM viability staining and DNA quantification. Data revealed the viability of the bone tissue over the tested time period of 28 days, and an increase in cell numbers implicating active cell proliferation processes in the sections. To analyze the bone regeneration potential of this model in combination with a bone replacement material, we injected a collagen-type 1 hydrogel into the central defect. Cellular ingrowth into the gel was evaluated by microscopy and DNA quantification at different time points demonstrating an increase of cells in the defect over time. Finally, gene expression of osteogenic markers indicated an osteoblastic phenotype of the cells in the defect. In summary, the ex vivo bone defect model remains viable and shows active bone repair processes over 28 days. Additional advantages include high reproducibility, manageable costs, and a native bone-implant interface supporting the evaluation of bone substitute materials and associated regeneration processes. Impact statement Testing of new implant materials and bone repair strategies up to date rely mainly on in vivo and in vitro investigation models providing different pros and cons. In this study we established a novel human ex vivo bone defect model with a proven vitality of at least 28 days. The model provides a native bone implant interface and is designed to monitor cell invasion into a critically sized defect filled with the potential implant material. Furthermore, associated repair processes can be documented on the cell and molecular level, including additional advantages such as high reproducibility and manageable costs.

Guided and Unguided Biopsy in the Diagnostic of Periprosthetic Infections of the Knee - Evaluation of an Evidence-based Algorithm. / Die gezielte und ungezielte Zupfbiopsie in der Abklärung periprothetischer Kniegelenksinfektionen ­ Evaluierung eines evidenzbasierten Algorithmus.

BACKGROUND: Periprosthetic joint infection (PPI) is one of the most common reasons for revision in total knee arthroplasty (TKA). Percutaneous synovial biopsy is considered as a well-established diagnostic tool in ambiguous cases of chronic pain after TKA. The exact number of undetected low-grade infections remains unclear. OBJECTIVES: The aim of this prospective study was to compare the diagnostic accuracy of arthroscopically guided and unguided synovial biopsy. Additionally, the prevalence of initially undetected PPI during synovial biopsy and revision surgery was assessed. MATERIALS AND METHODS: 40 patients suffering from chronic pain after TKA and the clinical suspicion of PPI were included in the study. Synovial biopsies were collected in a standardized manner first without and then with arthroscopic visual control. Using both techniques, six samples were collected each (5 for microbiology, 1 for histology). 19 patients, initially classified aseptic, underwent revision surgery later. RESULTS: The diagnosis of PPI was made in 10.0% of unguided biopsies (4 cases, 2× microbiologically, 2× histologically), 7.5% of arthroscopic biopsies (3 cases, 3× histologically) and 12.5% (5 cases, 3× histologically, 2× microbiologically) of all cases. Only histologic evaluation led to concordant positive findings using both techniques in two patients. The proportion of non-representative biopsies was twice as high after unguided tissue collection than after arthroscopic biopsy (30.0 vs. 15.0%). Microbiologic evaluation of arthroscopically collected biopsies did not lead to the diagnosis of PPI, which might have been essential to the selection of the appropriate antimicrobial therapy. During revision surgery the diagnosis of PPI was made in 22.2% of cases. CONCLUSIONS: In patients suffering from chronic pain after TKA, periprosthetic low-grade infection was diagnosed in a relevant proportion of cases. Therefore, synovial biopsies for histological and microbiological evaluation should be collected whenever there's clinical suspicion of PPI. For histological evaluation, samples should be collected using arthroscopic control and ideally multiple biopsies should be taken. For microbiological evaluation, excessive joint lavage should be avoided.

A 30-Year Single-center Experience of Cementless Total Hip Arthroplasty With Spongy Metal Structured Implants: A Follow-up of a Previous Report.

BACKGROUND/AIM: The aim of this study was to analyze survivorship and functional outcome of cementless spongy metal structured total hip arthroplasty (THA) after ultra-long-term follow-up. PATIENTS AND METHODS: A total of 100 THAs in patients under 65 years at initial surgery were performed between 1985 and 1989 at our Department. Twenty patients (23 hips) were available for final follow-up. Implant survivorship and functional results (Merle d'Aubigné, SF-12) were assessed. RESULTS: At a mean follow-up of 30 years (range=27.7-31.7 years), the overall stem survival rate was 82.6% (19/23 stems) and the overall cup survival rate was 52.2% (12/23 cups). Revision surgeries were performed for aseptic loosening in all cases. Functional evaluation revealed good to excellent results in 16 patients (80%) Conclusion: Spongy metal structured cementless THA provides remarkable survivorship and excellent functional results even after ultra-long-term follow-up. Further research regarding modern implants, bearing surfaces etc. is required to assess survivorship and clinical outcomes of different implant designs.

Electromagnetic transduction therapy and shockwave therapy in 86 patients with rotator cuff tendinopathy: A prospective randomized controlled trial.

Rotator cuff (RC) tendinopathy is the most common cause of shoulder pain. The effectiveness of electromagnetic transduction therapy (EMTT), a high energetic pulsed electromagnetic field therapy in this field has not been tested yet in combination with extracorporeal shock wave therapy (ESWT). A total of 86 patients with RC tendinopathy were randomized to undergo three sessions of ESWT in combination with 8 sessions of EMTT or sham-EMTT. Both intervention groups experienced significant and clinical relevant decrease of pain at all follow-up visits, and the functionality of the shoulder evaluated by the Constant Murley score increased significantly as well. The combination of EMTT + ESWT produced significantly greater pain reduction in the visual analogue scale compared to ESWT with sham-EMTT after 24 weeks, during which the Constant Murley score improved significantly when the combination of ESWT and EMTT was employed. In patients with RC tendinopathy, electromagnetic transduction therapy combined with extracorporeal shock wave therapy significantly improves pain and function compared to ESWT with sham-EMTT.

Distribution patterns of foot and ankle tumors: a university tumor institute experience.

BACKGROUND: Bone and soft tissue masses of the foot and ankle are not particularly rare but true neoplasia has to be strictly differentiated from pseudotumorous lesions. Diagnosis is often delayed as diagnostic errors are more common than in other regions. Awareness for this localization of musculoskeletal tumors is not very high and neoplasia is often not considered. The purpose of this study is to provide detailed information on the incidence and distribution patterns of foot and ankle tumors of a university tumor institute and propose a simple definition to facilitate comparison of future investigations. METHODS: As part of a retrospective, single-centre study, the data of patients that were treated for foot and ankle tumors between June 1997 and December 2015 in a musculoskeletal tumor centre were analyzed regarding epidemiologic information, entity and localization. Included were all cases with a true tumor of the foot and ankle. Exclusion criteria were incomplete information on the patient or entity (e.g. histopathological diagnosis) and all pseudotumoral lesions. RESULTS: Out of 7487 musculoskeletal tumors, 413 cases (5,52%) of tumors of the foot and ankle in 409 patients were included (215 male and 198 female patients). The average age of the affected patients was 36 ± 18y (min.3y, max.92y). Two hundred sixty-six tumors involved the bone (64%), among them 231 (87%) benign and 35 (13%) malignant. There were 147 soft tissue tumors (36%), 104 (71%) were benign, 43 (29%) malignant. The most common benign osseous tumor lesions included simple bone cysts, enchondroma and osteochondroma. By far the most common malignant bone tumor was chondrosarcoma. Common benign soft tissue tumors included pigmented villo-nodular synovitis, superifcial fibromatosis and schwannoma whereas the most common malignant members were synovial sarcoma and myxofibrosarcoma. Regarding anatomical localization, the hindfoot was affected most often. CONCLUSIONS: Knowledge of incidence and distribution patterns of foot and ankle tumors will help to correctly assess unclear masses and initiate the right steps in further diagnostics and treatment. Unawareness can lead to delayed diagnosis and inadequate treatment with serious consequences for the affected patient.

Is total femoral replacement for non-oncologic and oncologic indications a safe procedure in limb preservation surgery? A single center experience of 22 cases.

BACKGROUND: Several surgical options for the reconstruction of massive bone defects have been described and include biologic methods with autografts and allografts, and the use of tumor endoprostheses (total femoral replacement, TFR). Several types of modular TFR are available, but nevertheless unpredictable outcomes and high complication rates have been described from most authors. The present study aims to compare results after TFR performed with modular total femur prosthesis MML (Fa. ESKA/Orthodynamics) in patients with and without malignant disease. METHODS: Retrospective chart review and functional investigation (Musculoskeletal Tumor Society (MSTS) score, Harris Hip Score (HHS), Oxford Knee Score (OKS), SF-12 Health Survey, and failure classification according to Henderson) of TFR cases from 1995 to 2011. Indications for TFR were malignant tumor resection from the femur (n = 9, Group A) or failure of a revision arthroplasty without history of malignant disease (n = 13, Group B). RESULTS: Thirty-six patients were treated during the study period, of whom 22 could be investigated clinically after a mean follow-up of 63 months. Overall failure rate for TFR was 59.1%, leading to 38 surgical revisions. The most common failure mechanisms were Type I (soft tissue), followed by Type IV (infection) and Type III (mechanical failure). Mean MSTS score out of 30 was 13 (range 1-25), with significantly higher scores in Group A (mean 19, range 3-25) than Group B (mean 9, range 1-15). CONCLUSION: TFR is an established procedure to restore femoral integrity. However, complication rates are considerably high, and depend mainly on the age at initial reconstruction.

How to address ischiofemoral impingement? Treatment algorithm and review of the literature.

Ischiofemoral impingement (IFI) is a rare cause of hip pain defined by a narrowing of the space between the lateral aspect of the os ischium and the lesser trochanter of the femur. Several underlying anatomic, functional and iatrogenic pathologies have been identified for symptomatic IFI in native hip joints and after total hip arthroplasty. Clinical symptoms vary but most commonly consist of pain of the lower buttock and groin including the inner thigh, and a snapping or clunking phenomenon is often reported. Symptoms may be provoked by a combined extension, adduction and external rotation during physical examination and during long-stride walking. Radiographs of the pelvis and an axial or false-profile-view of the hip as well as magnetic resonance imaging (MRI)-scans should be obtained to strengthen the diagnosis. On MRI, the quadratus femoris muscle signal and the space confined by the anatomic structures surrounding the muscle, the quadratus femoris space, are to be assessed. Targeted infiltration of the muscle can be helpful both diagnostically and therapeutically. The literature on differential diagnoses and treatment options for IFI is limited; therapeutic suggestions are offered only in case reports and series. With this work, we aim to give a systematic approach to the non-surgical and surgical treatment options for IFI based upon the current literature and the authors' personal experience.

Treatment of Plantar Fasciitis With Radial Soundwave "Early" Is Better Than After 6 Months: A Pilot Study.

Extracorporeal shock wave therapy/radial soundwave therapy has been predominantly used for chronic or recalcitrant plantar fasciitis with strong scientific evidence of reliable outcomes. Most of the studies included patients with plantar fasciitis with symptoms >6 months in duration. Only 2 known studies have investigated acute plantar fasciitis, which is <6 weeks in duration. They both found suboptimal results for the use of extracorporeal shock wave therapy. To the best of our knowledge, no studies have investigated radial soundwave therapy for the subacute stage or early stage of plantar fasciitis. Data were prospectively collected from 28 eligible patients who underwent radial soundwave therapy (RSWT) during a 9-month period in 2014. Of the 28 subjects, 14 were enrolled in the "early group" with a symptom duration of <3 months and 14 in the "standard/control" group with a symptom duration of >6 months. The pretreatment and posttreatment visual analog scale scores, Roles-Maudlsey scores, and activity level were recorded and compared. The early implementation of RSWT yielded comparable outcomes when compared with the standard group. RSWT is a valid treatment modality that can be implemented soon after the initial treatment options or first-phase treatment options have failed. Early treatment is more likely to allow for maintenance of patients' activity level. Also, waiting 6 months to treat plantar fasciitis with RSWT results in delays and inferior results. Early treatment is better for active and athletic patients.

Electromagnetic Transduction Therapy for Achilles Tendinopathy: A Preliminary Report on a New Technology.

A parallel prospective feasibility study was performed on 53 patients with chronic mid-portion Achilles tendinopathy (age 44.7 ± 9.1 years). Of the 53 patients, 28 (active group) were treated using a new electromagnetic (pulsed electromagnetic field) transduction therapy device (Cellactor® MT1) and heel cushions. The device produces an electromagnetic field of 80 milliTesla; a total of 8 treatments was performed within 4 weeks in an outpatient setting, without anesthesia, immobilization, or rest. A control group of 25 patients with a similar duration of symptoms was treated with heel cushions only. At the 12-week assessment point, the visual analog scale scores in both groups had significantly decreased, although the active group had significantly improved visual analog scale scores compared with those of the controls. The Role-Maudsley scores had also significantly improved in both the active and the control groups (p < .00001 and p = .0002, respectively). Electromagnetic transduction therapy could potentially be a useful modality for the treatment of Achilles tendinopathy. It should be compared with the current reference standard of extracorporeal shockwave therapy/radial soundwave therapy with similar level I, II, and III studies.

Treatment of Medial Tibial Stress Syndrome With Radial Soundwave Therapy in Elite Athletes: Current Evidence, Report on Two Cases, and Proposed Treatment Regimen.

Two case reports of high-level athletes with medial tibial stress syndrome (MTSS), 1 an Olympian with an actual stress fracture, are presented. Successful treatment included radial soundwave therapy, pneumatic leg braces, relative rest using an antigravity treadmill, and temporary foot orthoses. Radial soundwave therapy has a high level of evidence for treatment of MTSS. We also present recent evidence of the value of vitamin D assessment. Both patients had a successful outcome with minimal downtime. Finally, a suggested treatment regimen for MTSS is presented.

Electromagnetic transduction therapy in non-specific low back pain: A prospective randomised controlled trial.

OBJECTIVES: A prospective randomised controlled trial to investigate the efficacy of electromagnetic transduction therapy (EMTT) for treatment of patients with non-specific low back pain. DESIGN: Two groups with non-specific low back pain were either treated with conventional therapy alone over 6 weeks or in combination with 8 sessions of EMTT. RESULTS: In both intervention groups the low back pain related pain and the degree of disability decreased significantly at follow-up visits. Combination of EMTT and conventional therapy proved significant superior to conventional therapy alone. CONCLUSION: EMTT is a promising treatment in patients with non-specific low back pain.

Randomized Placebo-Controlled Placebo Trial to Determine the Placebo Effect Size.

BACKGROUND: It is the gold standard to use a placebo treatment as the control group in prospective randomized controlled trials (RCTs). Although placebo-controlled trials can reveal an effect of an active treatment, the pure effect of a placebo treatment alone has never been presented or evaluated. No evidence-based, placebo-therapeutic options are currently available, and no placebo-controlled trials have been performed to elucidate the pure placebo effect. OBJECTIVES: To analyze the pure placebo effect on clinical, chronic pain through a blinded RCT. STUDY DESIGN: A prospective, randomized, placebo-controlled trial. SETTING: Medical University centers. METHODS: One-hundred eighty-two patients suffering from chronic plantar heel pain for over 6 months,who failed to respond to conservative treatments, were screened and 106 of these patients were enrolled into this study. The patients were randomly assigned to receive either a blinded placebo shockwave treatment or an unblinded placebo shockwave treatment. The primary outcome measure was the differences in percentage change of visual analogue scale (VAS) scores 6 weeks after the intervention. The secondary outcome measure was the differences in Roles and Maudsley pain score (RMS) 6 weeks after intervention. As an exploratory outcome, 2-sided group comparisons for baseline characteristics between active treatment and controls were done using the Mann-Whitney-U tests for group comparisons; treatment efficiency was calculated by the effect size coefficient and benchmarks for the Mann-Whitney estimator according to the t-test of 2 independent samples for quantitative data, as well as the Fisher's exact test for binary data. RESULTS: Patients from both groups did not differ with respect to heel pain ratings at baseline, for both the VAS (P = .476) and RMS (P = .810) scores. After 6 weeks, patients receiving the blinded placebo treatment reported less heel pain on both scales (VAS: P = .031; RMS: P = .004). Change scores of pain ratings were significantly higher in the blinded placebo group than in the un-blinded placebo group (VAS: P = .002; RMS: P = .002). LIMITATIONS: As the study represents the first to use an inverse placebo RCT (IPRCT), further conceptual and methodological issues need to be addressed to describe detailed, underlying mechanisms. Specific contextual, intrapersonal, and interpersonal factors modulating the placebo effects should be addressed in future IPRCTs. CONCLUSIONS: The present study indicated that true placebo effect sizes can be analyzed through a proper IPRCT design. Instead of treating high numbers of patients with placebos in a RCT, which increases the risk for subjects not receiving the active treatment, the IPRCT technique seems to be much more appropriate to analyze the effect sizes of any active treatment, in accordance with the Good Clinical Practice guidelines and Declarations of Helsinki. KEY WORDS: Pain, randomized controlled trial, RCT, placebo, effect size, inverse placebo, study, pain therapy.